you can also use presets to encode your video (ffmpeg2theora -p help for more info)

ffmpeg2theora -p preview videoclip.dv

or

ffmpeg2theora -p pro videoclip.dv

on linux you can use ffmpeg2theora to stream to an icecast server:
this needs the latest version of the icecast server and a
small tool to send the ogg stream to the icecast server.
a more detailed description can be found in the Streaming HowTo